Efficacy of minimally invasive surgery on hallux valgus – A systematic review and meta-analysis

Abstract

Introduction: The evolution of minimal incision surgery for hallux valgus has led to some of many procedures being performed minimally invasively, with no definitive consensus on which technique is more effective. The aim of this study is to systematically search the literature in order to evaluate the effect of minimally invasive surgery over conventional open surgery for hallux valgus with respect to surgical outcomes and patient reported outcomes.

Methods: Medline Complete, PubMed, Cochrane Library, Scopus, SAGE Journals and gray literature were searched. We considered Randomised Controlled Trials and observational studies with a comparison arm. Primary outcomes focused on hallux valgus angle, intermetatarsal angle, distal metatarsal articular angle. Secondary Outcomes included the American Foot & Ankle Society Score (AOFAS), as well as Pain on a Visual Analogue Scale(VAS), patient satisfaction, complications, SF-36 questionnaire and Manchester Oxford Foot Questionnaire (MOXFQ).  The inclusion criteria included patients with primary diagnosis of hallux valgus and no other co-morbidities. Subgroup analysis allowed for more accurate meta-analysis based on surgical technique to remove potential confounding due to heterogeneity. Effect estimates were summarized using Mantel-Haenszel meta-analysis and odds ratios or mean differences with respective 95% confidence intervals (CI) were calculated.

Results: 8 randomized trials and 7 cohort studies were identified. A total of 907 patients were included with a mean age of 48 years.  Radiological outcomes between similar techniques (comparing MIS and Open) were found to have no significant difference pre and post operatively at final follow up (6 months to 5 years).  Visual analogue scale scores were found to be significantly lower in the MIS groups compared to open techniques (MICA v Scarf) in the short term at Day 1 (P<0.00001) MD= -1.96 95% CI: -2.28, -1.65; I² = 0%; Week 2 (P=0.001) MD= -1.40; 95% CI: -2.26, -0.54;  and Week 6 (P=0.005) MD= -1.50; 95% CI: -2.55, -0.45. There was no statistical difference at 6 months (3 studies) (P=0.46) MD= -0.16; 95% CI: -0.59, 0.27; I² = 0%; or final follow up (6 m to >24m) (P=0.94) MD= -0.02; 95% CI: -0.44, 0.41; I² = 0%.).  There were no statistically important differences between post-operative AOFAS scores across comparisons, whereas AOFAS mean difference was found to be significantly higher in Open Scarf vs MICA (P = 0.003); MD=-5.54; 95% CI: -9.19, -1.88. I² = 0%.

Conclusion: The present review found that Open Scarf resulted in a higher mean difference AOFAS score compared with MICA, while post-operative scores at final follow up were statistically insignificant. The data also showed that early post-operative VAS scores were significantly better in the MICA group compared to the Open Scarf.  Randomised and observational evidence on long term follow up is awaited.